出典:Wiktionary
出典:『Wiktionary』 (2026/04/24 23:22 UTC 版)
| Chemical element |
|---|
| Th Atomic number 90 thorium |
| Previous: ← actinium (Ac) |
| Next: protactinium (Pa) → |
| English Wikipedia article on Thorium |
thorium (usually uncountable, plural thoriums)
| Chemical element |
|---|
| Th Atomic number 90 thorium |
| Previous: ← actinium (Ac) |
| Next: protactinium (Pa) → |
出典:Wikipedia
出典:『Wikipedia』 (2011/07/26 10:10 UTC 版)
Thorium (
/ˈθɔriəm/ thohr-ee-əm) is a naturally occurring radioactive chemical element, found in abundance throughout the world. Thorium atoms (symbol Th) have an atomic number of 90, with 90 protons and 90 electrons, of which 4 are valence electrons. It was discovered in 1828 and named after Thor, the Norse god of thunder.
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